Electric power supply system

ABSTRACT

According to one embodiment, an electric power supply system includes a processor, a power circuit and an embedded controller. The processor includes a first controller configured to modify an operating frequency of the processor and a second controller configured to modify an operating power of the processor. The power circuit and the embedded controller detect a presence or an absence of a battery in parallel. The power circuit instructs the first controller to modify the operating frequency when removal of the battery is detected. The embedded controller causes the second controller to modify the operating power via a Basic Input/Output System (BIOS) when the removal of the battery is detected, and causes the first controller to stop modify the operating power via the power circuit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 16/216,556, filed Dec. 11, 2018, which is based upon and claimsthe benefit of priority from Japanese Patent Application No.2017-240780, filed Dec. 15, 2017, the entire contents of which areincorporated herein by reference.

FIELD

Embodiments described herein relate generally to an electric powersupply system.

BACKGROUND

In recent years, battery-powered electronic apparatuses such as anotebook personal computer (PC), tablet PC, smartphone, and the like arevariously utilized. An electronic apparatus of this kind is generallyconfigured to be able to operate by power from either an AC adaptor or abattery.

Further, recently, an electric power supply architecture in which whenpower consumed by a load exceeds power from an AC adaptor, the shortfallis supplemented with power from a battery without exclusively andselectively using power from an AC adaptor or power from a battery isbeginning to be widespread. As one of the electric power supplyarchitectures of this kind, a Narrow VDC (NVDC) is known.

When an electric power supply system is constructed in accordance withthe construction of the NVDC or the like which is an electric powersupply architecture that can be dependent upon power from a battery evenunder circumstances where power is supplied from an AC adaptor, it ispossible to cope with the event that the power consumed by the loadexceeds the power from the AC adaptor, but on the other hand, measuresor the like to cope with, for example, the event that the battery isremoved under circumstances where power is supplied from the AC adaptorare newly required.

BRIEF DESCRIPTION OF THE DRAWINGS

A general architecture that implements the various features of theembodiments will now be described with reference to the drawings. Thedrawings and the associated descriptions are provided to illustrate theembodiments and not to limit the scope of the invention.

FIG. 1 is a view showing an example of a configuration of an electricpower supply system of a first embodiment.

FIG. 2 is a view showing transition examples of a state associated withelectric power in a case where a battery of the electric power supplysystem of the first embodiment is removed.

FIG. 3 is a flowchart showing an example of an operation procedure ofthe electric power supply system of the first embodiment.

FIG. 4 is a view showing an example of setting associated with the powerconsumption of the CPU by the BIOS of an electric power supply system ofa second embodiment.

FIG. 5 is a flowchart showing an example of an operation procedure ofthe electric power supply system of the second embodiment.

FIG. 6 is a view showing an example of setting of a current limit valueto a charger IC performed by an embedded controller of an electric powersupply system of a third embodiment.

FIG. 7 is a flowchart showing an example of an operation procedure ofthe electric power supply system of the third embodiment.

FIG. 8 is a view showing an example of a configuration of a system powercontrol section in an electric power supply system of a fourthembodiment.

FIG. 9 is a view showing an example of setting of a system power voltagevalue to a charger IC by an embedded controller of the electric powersupply system of the fourth embodiment.

FIG. 10 is a view showing the power supply efficiency of each voltagevalue of the system power of the electric power supply system of thefourth embodiment.

FIG. 11 is a flowchart showing an example of an operation procedure ofthe electric power supply system of the fourth embodiment.

FIG. 12 is a view showing transition of a system current of a case wherethe voltage value of the system power is restored to the specificationvalue of the battery concomitantly with attachment of the battery of theelectric power supply system of the fourth embodiment.

FIG. 13 is a flowchart showing an example of an operation procedure ofan electric power supply system of a fifth embodiment.

FIG. 14 is a view showing an example of setting of a system powervoltage value to a charger IC by an embedded controller of an electricpower supply system of a sixth embodiment.

FIG. 15 is a flowchart showing an example of an operation procedure ofthe electric power supply system of the sixth embodiment.

FIG. 16 is a view showing an example of a configuration of an electricpower supply system of a seventh embodiment.

FIG. 17 is a flowchart showing an example of an operation procedure ofthe electric power supply system of the seventh embodiment.

DETAILED DESCRIPTION

In general, according to one embodiment, an electric power supply systemincludes a processor, a power circuit and an embedded controller. Theprocessor includes a first controller configured to modify an operatingfrequency of the processor and a second controller configured to modifyan operating power of the processor. The power circuit detects apresence or an absence of a battery, creates a third power output tooutput to a load comprising the processor using a first power from anadaptor and a second power from the battery, and outputs the third powerto the load comprising the processor. The embedded controller detectsthe presence or the absence of the battery at least partially inparallel with detection by the power circuit. The power circuitinstructs the first controller to modify the operating frequency, andinstructs the first controller to stop modifying the operating frequencyaccording to an instruction from the embedded controller when the powercircuit detects removal of the battery. The embedded controller causesthe second controller to modify the operating power by notifying a BasicInput/Output System (BIOS) of removal of the battery when the embeddedcontroller detects the removal of the battery, and instructs the powercircuit to instruct the first controller to stop modifying the operatingfrequency of the processor after causing the second controller to modifythe operating power. The BIOS includes a program executed by theprocessor.

Hereinafter, embodiments will be described with reference to theaccompanying drawings.

First Embodiment

First, a first embodiment will be described below.

FIG. 1 is a view showing an example of a configuration of an electricpower supply system (NVDC electric power supply system 1) of thisembodiment.

The NVDC electric power supply system 1 adaptively uses both power (a1)from an AC adaptor 11 and power (a2) from a battery pack 12 to createand output system power (a3) for the load including a CPU 14. This NVDCelectric power supply system 1 is applicable to any electronic apparatusif the electronic apparatus is an apparatus to which power can besupplied by use of an AC adaptor 11, and a battery pack 12 can beattached such as a notebook PC, tablet PC, smartphone, and the like. Itshould be noted that here a case where this NVDC electric power supplysystem 1 is applied to a notebook PC to/from which an extension unit(Dock) incorporating therein an Optical Disc Drive (ODD) can be freelyattached/detached is assumed. Further, each of the notebook PC andextension unit includes a connector for connection to the AC adaptor 11and, in a state where the extension unit is not attached to the notebookPC, the main body side AC adaptor 11A is connected to the connector ofthe notebook PC and, in a state where the extension unit is attached tothe notebook PC, the Dock side AC adaptor 11B is connected to theconnector of the extension unit. It should be noted that it is alsopossible to cause the main body side AC adaptor 11A to be connected tothe connector of the extension unit in the state where the extensionunit is attached to the notebook PC. Here, it is assumed that the mainbody side AC adaptor 11A and Dock side AC adaptor 11B are different fromeach other in rating (supply rating). More specifically, the rating ofthe Dock side AC adaptor 11B regarding which it is conceivable thatpower is consumed by the ODD and the like is set larger than the ratingof the main body side adaptor 11A. That is, in the NVDC electric powersupply system 1, power is input from the plurality of AC adaptors 11(11A and 11B) different from each other in rating. It should be notedthat the power from the AC adaptor 11 is also used for charging of thebattery pack 12.

As shown in FIG. 1, the NVDC electric power supply system 1 is realizedby the cooperation of a power circuit 13, processor (Central ProcessingUnit (CPU)) 14, and embedded controller (EC) 15, and BIOS 16 which is aprogram executed by the CPU 14.

The power circuit 13 includes a system-power supply control unit 131,and charger IC 132.

The system-power supply control unit 131 of the power circuit 13 usesthe power from the AC adaptor 11 and power from the battery pack 12 tocreate and output the system power under the control of the charger IC132. When the AC adaptor 11 is connected to the power circuit 13, andthe battery pack 12 is attached to the power circuit 13, the voltagevalue of the system power is set to the full-charge voltage value of thebattery pack 12. The voltage value of the system power may be changed bythe setting of the charger IC 132 performed by the embedded controller15.

The charger IC 132 is a module which controls charge and discharge ofthe battery pack 12. When the power consumed by the load exceeds therating of the AC adaptor 11, the charger IC 132 performs control in sucha manner that the shortfall is supplemented with power from the batterypack 12. The charger IC 132 includes an AC adaptor detecting unit 1321,battery pack detecting unit 1322, and power control unit 1323.

The AC adaptor detecting unit 1321 detects presence/absence ofconnection of the AC adaptor 11 and, more specifically, detectspresence/absence of input of power from the AC adaptor 11. The ACadaptor detecting unit 1321 detects presence/absence of connection ofthe AC adaptor 11 according to, for example, a voltage value of apower-supply line for the AC adaptor 11 and, more specifically,according to presence/absence of an applied voltage thereof. The ACadaptor detecting unit 1321 does not perform determination of the ACadaptor 11. Further, the AC adaptor detecting unit 1321 detects acurrent value of power from the AC adaptor 11. The charger IC 132monitors the current value and, when detecting that the power consumedby the load exceeds the rating of the AC adaptor 11, discharges thebattery pack 12 to supplement the shortfall. The detection of thecharger IC 132 is performed by monitoring whether or not the currentvalue exceeds the current limit value set by the embedded controller 15.The charger IC 132, embedded controller 15, and battery pack 12 cancommunicate with each other through the I²C bus, and the embeddedcontroller 15 performs setting of the current limit value for thecharger IC 132 by the communication through the I²C bus.

The battery pack detecting unit 1322 detects presence/absence ofattachment of the battery pack 12. The battery pack detecting unit 1322monitors, for example, a signal line which is derived from the PC mainbody to the battery pack 12 when the battery pack 12 is attached to thePC main body, and which is pulled up by the battery pack 12 to detectpresence/absence of attachment of the battery pack 12.

The power control unit 1323 performs various setting operations for thesystem-power supply control unit 131. As one of the setting items, avoltage value of the aforementioned system power to be output isincluded.

The CPU 14 includes a frequency control unit 141 and power control unit142 with regard to the NVDC electric power supply system 1.

In response to the input of a frequency throttling signal via apredetermined input/output pin among a plurality of input/output pinsprovided in the CPU 14, the frequency control unit 141 performs firstcontrol for making the operating frequency of the CPU 14 the lowestfrequency or for restoring the operating frequency from the lowestfrequency to the normal frequency. The first control of the frequencycontrol unit 141 can reduce the power consumption of the CPU 14 byshifting the operating frequency of the CPU 14 to the lowest frequency.

The power control unit 142 performs second control for operating the CPU14 by the power set by the BIOS 16. More specifically, the CPU 14 hastwo operating modes including a normal mode and high-load mode, and thepower control unit 142 controls the power consumption of the CPU 14 foreach mode. The second control of the power control unit 142 can reducethe power consumption of the CPU 14 by limiting the power consumption ofthe CPU 14.

The embedded controller 15 includes an AC adaptor A/D converting unit151 and battery pack detecting unit 152 with regard to the NVDC electricpower supply system 1.

The embedded controller 15 digitizes the voltage value of the power fromthe AC adaptor 11 by use of the AC adaptor A/D converting unit 151. Theembedded controller 15 determines based on the digitized value whetheror not the AC adaptor 11 is connected, and determines the type of the ACadaptor 11, e.g., whether the AC adaptor 11 is the main body side ACadaptor 11A or the Dock side AC adaptor 11B. The AC adaptor A/Dconverting unit 151 is a module unique to the embedded controller 15 ofthe NVDC electric power supply system 1, and how the embedded controller15 utilizes the result of the determination of the type of the ACadaptor 11 based on the digitized value will be described in detail inanother embodiment to be described later.

The battery pack detecting unit 152 detects presence/absence ofattachment of the battery pack 12 as in the case of the battery packdetecting unit 1322 of the charger IC 132. When the battery pack 12 isattached to the PC, the embedded controller 15 can acquire theinformation about the remaining battery level of the battery pack 12through the I²C bus.

With regard to the NVDC electric power supply system 1, the BIOS 16includes a power setting unit 161. The power setting unit 161 performssetting for the power control unit 142 of the CPU 14 and, morespecifically, sets the power consumption in each of the aforementionednormal mode and high-load mode.

Next, an example of an operation of the NVDC electric power supplysystem 1 of this embodiment having the aforementioned configuration inthe case where the battery pack 12 thereof is removed will be describedbelow.

Now a case where under the circumstances in which power from the ACadaptor 11 is input to the NVDC electric power supply system 1, and thebattery pack 12 has been attached thereto, the battery pack 12 isremoved is assumed. In this case, when the power exceeding the rating ofthe AC adaptor 11 is consumed by the load, the shortfall cannot besupplemented with the power from the battery pack 12, and hence there isa possibility of the system shutdown being caused by the exceeding ofthe rating of the AC adaptor 11.

Normally, in this case, the embedded controller which has detected theremoval of the battery pack 12 by use of the battery pack detecting unit152 notifies the BIOS 16 of an electric power saving setting event, andthe power setting unit 161 of the BIOS 16 which has received thenotification performs setting for controlling the CPU 14 in such amanner that the power consumption of the CPU 14 does not exceed therating of the AC adaptor 11 for the power control unit 142 of the CPU14.

Here, the issuance of the notification from the embedded controller 15to the BIOS 16 is performed by, for example, the firmware (program) ofthe embedded controller 15 by supplying an interrupt signal to the CPU14. Setting for the power control unit 142 of the CPU 14 performed bythe firmware of the embedded controller 15 or by the program of the BIOS16 or the like requires a predetermined length of time. Accordingly,when the battery pack 12 is removed, if power exceeding the rating ofthe AC adaptor 11 is consumed by the load or if power exceeding therating of the AC adaptor 11 is consumed by the load before the settingfor the power control unit 142 is performed, there is a possibility ofthe system shutdown being caused by the exceeding of the rating of theAC adaptor 11.

Thus, in the NVDC electric power supply system 1 of this embodiment, inparallel with the operation of the embedded controller 15, the chargerIC 132 which has detected that the battery pack 12 is removed by use ofthe battery pack detecting unit 1322 provided in the power circuit 13instructs the frequency control unit 141 of the CPU 14 to temporarilymake the operating frequency of the CPU 14 the lowest frequency (a11 inFIG. 1). It should be noted that in parallel with the operation of thecharger IC 132, setting for controlling the CPU 14 in such a manner thatthe power consumption of the CPU 14 does not exceed the rating of the ACadaptor 11 for the power control unit 142 of the CPU 14 by the firmwareof the embedded controller 15 or by the program of the BIOS 16 or thelike is also performed as usual (a12 and a13 in FIG. 1).

Upon receipt of this instruction, the frequency control unit 141 of theCPU 14 immediately makes the operating frequency of the CPU 14 thelowest frequency. Thereby, it is possible to securely prevent the systemshutdown from being caused by the exceeding of the rating of the ACadaptor 11. On the other hand, continuing of the CPU 14 to operate atthe lowest frequency causes, for example, deterioration or the like inthe response to the user operation, and hence it is desirable that theoperating frequency of the CPU 14 be restored to the original operatingfrequency after setting for controlling the CPU 14 in such a manner thatthe power consumption of the CPU 14 does not exceed the rating of the ACadaptor 11 is performed. Thus, upon receipt of a reply expressing thatthe setting has been completed from the BIOS 16 (a14 in FIG. 1), theembedded controller 15 instructs the charger IC 132 to cancel thecontrol for limiting the operating frequency of the CPU 14 to the lowestfrequency (a15 in FIG. 1). The charger IC 132 which has received theinstruction instructs the frequency control unit 141 of the CPU 14 torestore the operating frequency of the CPU 14 to the original operatingfrequency (a16 in FIG. 1).

FIG. 2 is a view showing examples of transition of the state associatedwith power of a case where under the circumstances in which power fromthe AC adaptor 11 is input to the NVDC electric power supply system 1,and the battery pack 12 is attached thereto, the battery pack 12 isremoved.

In FIG. 2, (A) indicates an example of transition of the stateassociated with power of a case where issuance of an instruction totemporarily make the operating frequency of the CPU 14 the lowestfrequency to the frequency control unit 141 of the CPU 14 is notperformed by the charger IC 132.

As indicated by (A) of FIG. 2, if the power exceeding the rating of theAC adaptor 11 is consumed by the load when the battery pack 12 isremoved, the setting for performing control in such a manner that thepower consumption does not exceed the rating of the AC adaptor 11 by aprogram such as the firmware of the embedded controller 15 or the BIOS16 for the power control unit 142 of the CPU 14 is too late, and thereis a possibility of the system shutdown being caused by the exceeding ofthe rating of the AC adaptor 11.

In FIG. 2, (B) indicates an example of transition of the stateassociated with power of a case where issuance of an instruction totemporarily make the operating frequency of the CPU 14 the lowestfrequency to the frequency control unit 141 of the CPU 14 is performedby the charger IC 132.

As indicated by (B) of FIG. 2, even if the power exceeding the rating ofthe AC adaptor 11 is consumed by the load when the battery pack 12removed, the frequency control unit 141 of the CPU 14 immediately makesthe operating frequency of the CPU 14 the lowest frequency in responseto an instruction from the charger IC 132, whereby the rating of the ACadaptor 11 is prevented from being exceeded.

FIG. 3 is a flowchart showing an example of an operation procedure ofthe NVDC electric power supply system 1 of this embodiment.

When the battery pack 12 is removed, the charger IC 132 instructs theCPU 14 to temporarily make the operating frequency thereof the lowestfrequency (step A1). In parallel with the operation of the charger IC132, the embedded controller 15 notifies the BIOS 16 of an electricpower saving setting event (step A2). Then, the BIOS 16 which hasreceived the notification from the embedded controller 15 performssetting for causing the power consumption not to exceed the rating ofthe AC adaptor 11 for the CPU 14 (step A3).

Upon completion of the setting for the CPU 14, the BIOS 16 instructs theembedded controller 15 to cancel the temporarily set limitation of theoperating frequency of the CPU 14 (step A4). This instruction istransmitted from the embedded controller 15 to the charger IC 132through the I²C bus. The charger IC 132 instructs the CPU 14 to restorethe operating frequency thereof to the original operating frequency(step A5).

As described above, the NVDC electric power supply system 1 of thisembodiment realizes the safe and efficient use of power from the ACadaptor and power from the battery.

Second Embodiment

Next, a second embodiment will be described below.

It is assumed that the configuration of an NVDC electric power supplysystem 1 of this embodiment is identical to the first embodiment (seeFIG. 1).

In the first embodiment, when the battery pack 12 is removed, thecharger IC 132 instructs the CPU 14 to operate at the lowest frequency,whereby the system shutdown is prevented from being caused by theexceeding of the rating of the AC adaptor 11 until setting of the CPU 14for preventing the power consumption from exceeding the rating of the ACadaptor 11 is completed. Conversely, the NVDC electric power supplysystem 1 of this embodiment prevents the system shutdown from beingcaused by the exceeding of the rating of the AC adaptor 11 even when theremaining battery level of the battery pack 12 falls below a thresholdin addition to when the battery pack 12 is removed as will be describedbelow. It should be noted that the temporary limitation of the operatingfrequency of the CPU 14 by the charger IC 132 described in the firstembodiment may also be performed at the same time.

As described in the first embodiment, the embedded controller 15 candetect presence/absence of connection of the AC adaptor 11 by use of avoltage value of the power from the AC adaptor 11 digitized by the ACadaptor A/D converting unit 151. Further, the embedded controller 15 candetect presence/absence of attachment of the battery pack 12 by use ofthe battery pack detecting unit 152. Furthermore, when the battery pack12 is attached, the embedded controller 15 can acquire information aboutthe remaining battery level of the battery pack 12 through the I²C bus.

When the battery pack 12 is removed or when the remaining battery levelof the battery falls below the threshold, the embedded controller 15 inthe NVDC electric power supply system 1 of this embodiment notifies theBIOS 16 of an electric power saving setting event, and shuts down thesupply of power to the USB device, ODD, keyboard backlight, and the likeeven when the AC adaptor 11 is connected.

The shutdown of the power supply to the USB device, ODD, keyboardbacklight, and the like by the embedded controller 15 is performedwithin a sufficiently short period of time as compared with the settingfor the CPU 14, which is performed through the route from the embeddedcontroller 15 to the BIOS 16 and to the CPU 14, for causing the powerconsumption not to exceed the rating of the AC adaptor 11, and hence itis possible to prevent the system shutdown from being caused by theexceeding of the rating of the AC adaptor 11.

FIG. 4 is a view showing an example of setting for the power controlunit 142 of the CPU 14 by the BIOS 16 which has received thenotification of the electric power saving setting event from theembedded controller 15 by use of the power setting unit 161.

As described in the first embodiment, the CPU 14 has two operating modesincluding a normal mode and high-load mode. The continuous mode in FIG.4 indicates the power consumption of the CPU 14 at the time of thenormal mode, and the peak mode indicates the power consumption of theCPU 14 at the time of the high-load mode. In other words, the powercontrol unit 142 controls the CPU 14 in such a manner that the CPU 14operates by the power indicated by the continuous mode at the time ofthe normal mode, and controls the CPU 14 in such a manner that the CPU14 operates by the power indicated by the peak mode at the time of thehigh-load mode. It should be noted that the period of time within whichthe CPU 14 can continuously operate in the high-load mode is limited.

As shown in FIG. 4, when the AC adaptor 11 is connected, the batterypack 12 is attached, and the remaining battery level of the battery pack12 is higher than or equal to the threshold, the BIOS 16, morespecifically, the power setting unit 161 sets the continuous mode to thenormal power, and sets the peak mode to the peak power. Assuming thatthe power from the AC adaptor 11 is power of such a degree that thepower is somewhat higher than the peak power, the power is also consumedby the load other than the CPU 14, and hence when the CPU 14 operates inthe high-load mode, there is a strong possibility of power from thebattery pack 12 being allocated for the operation. It should be notedthat when the battery pack 12 is attached, and the remaining batterylevel thereof is higher than or equal to the threshold or the remainingbattery level of the battery pack 12 has been restored to a value higherthan or equal to the threshold, the embedded controller 15 notifies theBIOS 16 of a maximum power setting event, and the BIOS 16 takes theopportunity of receiving the notification to perform the settingoperations.

On the other hand, when the battery pack 12 is removed or when theremaining battery level of the battery pack 12 falls below thethreshold, the BIOS 16 takes the opportunity of receiving thenotification of the electric power saving setting event from theembedded controller 15 to set the continuous mode to the minimum power(minimum power<normal power), and set the peak mode also to the minimumpower. Thereby, even when the CPU 14 operates in the high-load mode, thepower consumption falls within the range of the power from the ACadaptor 11, and hence the system shutdown is never caused by theexceeding of the rating of the AC adaptor 11.

FIG. 5 is a flowchart showing an example of an operation procedure ofthe NVDC electric power supply system 1 of this embodiment. Thisflowchart shows the operation procedures of the embedded controller 15and BIOS 16 in the case where a change in the connection (attachment)state of the AC adaptor 11 or the battery pack 12 or a change in thecapacity of the battery pack 12 has occurred.

The embedded controller 15 determines presence/absence of connection ofthe AC adaptor 11 (step B1). When the AC adaptor 11 is connected (YES instep B1), the embedded controller 15 determines this timepresence/absence of attachment of the battery pack 12 (step B2). Whenthe battery pack 12 is attached (YES in step B2), the embeddedcontroller 15 subsequently determines whether or not the remainingbattery level of the battery pack 12 is higher than or equal to thethreshold (step B3).

When the remaining battery level of the battery pack 12 is higher thanor equal to the threshold (YES in step B3), the embedded controller 15notifies the BIOS 16 of a maximum power setting event (step B4).Further, at this time, the embedded controller 15 performs control insuch a manner that supply of power to the USB device, ODD, keyboardbacklight, and the like is performed. The BIOS 16 which has received thenotification of the maximum power setting event from the embeddedcontroller 15 sets power consumption in each mode to the CPU 14, morespecifically, to the power control unit 142 (step B5).

When the battery pack 12 is removed (NO in step B2) or when theremaining battery level of the battery pack 12 falls below the threshold(NO in step B3), the embedded controller 15 notifies the BIOS 16 of anelectric power saving setting event (step B6). Further, at this time,the embedded controller 15 shuts down the supply of power to the USBdevice, ODD, keyboard backlight, and the like. The BIOS 16 which hasreceived the notification of the maximum power setting event from theembedded controller 15 sets power consumption in each mode to the CPU14.

When the AC adaptor 11 is not connected (NO in step B1), the embeddedcontroller 15 determines whether or not the discharge rating of thebattery pack 12 satisfies the system maximum load (step B7). Thisdetermination is performed based on, for example, whether or not thedischarge rating of the battery pack 12 acquired by the communicationthrough the I²C bus is greater than or equal to a predetermined value.When the discharge rating of the battery pack 12 does not satisfy thesystem maximum load (NO in step B7), the embedded controller 15 notifiesthe BIOS 16 of an electric power saving setting event (step B6).Further, at this time, the embedded controller 15 shuts down the supplyof power to the USB device, ODD, keyboard backlight, and the like. TheBIOS 16 which has received the notification of the maximum power settingevent from the embedded controller 15 sets power consumption in eachmode to the CPU 14. When the discharge rating of the battery pack 12satisfies the system maximum load (YES in step B7), the embeddedcontroller 15 notifies the BIOS 16 of a maximum power setting event(step B4). Further, at this time, the embedded controller 15 performscontrol in such a manner that the supply of power to the USB device,ODD, keyboard backlight, and the like is performed. The BIOS 16 whichhas received the notification of the maximum power setting event fromthe embedded controller 15 sets power consumption in each mode to theCPU 14 (step B5).

As described above, the NVDC electric power supply system 1 of thisembodiment realizes the safe and efficient use of power from the ACadaptor and power from the battery.

Third Embodiment

Next, a third embodiment will be described below.

It is assumed that the configuration of an NVDC electric power supplysystem 1 of this embodiment is identical to the first embodiment (seeFIG. 1).

As described in the first embodiment, the charger IC 132 detects acurrent value of power from the AC adaptor 11 by use of the AC adaptordetecting unit 1321, and monitors whether or not the current valueexceeds the current limit value set by the embedded controller 15. Whenthe current value exceeds the current limit value, i.e., when the loadconsumes power exceeding the rating of the AC adaptor 11, the charger IC132 discharges the battery pack 12 to supplement the shortfall.

Incidentally, in the NVDC electric power supply system 1 to which powerfrom a plurality of AC adaptors 11A and 11B different from each other inrating can be input, if the current limit value is determined by using,for example, the AC adaptor 11A having the lower rating as a criterion,when the AC adaptor 11B having the higher rating is connected, there isa possibility of essentially unnecessary discharge of the battery pack12 being performed.

Further, as described also in the first embodiment, based on a voltagevalue of the power from the AC adaptor 11 digitized by the AC adaptorA/D converting unit 151, the embedded controller 15 determinespresence/absence of connection of the AC adaptor 11, and the type of theAC adaptor 11, e.g., whether the AC adaptor 11 is the main body side ACadaptor 11A or the Dock side AC adaptor 11B.

Thus, in the NVDC electric power supply system 1 of this embodiment, theembedded controller 15 which determines the type of the AC adaptor 11switches the current limit value to be used in the charger IC 132according to the type of the AC adaptor 11.

FIG. 6 is a view showing an example of setting to the charger IC 132performed by the embedded controller 15 which determines the type of theAC adaptor 11.

In FIG. 6, the current limit 1 indicated by a reference symbol cl is thecurrent limit value and, when, for example, the main body side ACadaptor 11A having a rating of 45 W is connected, the embeddedcontroller 15 sets a current limit value for 45 W. Further, when, forexample, the Dock side AC adaptor 11B having a rating of 120 W or 180 Wis connected, the embedded controller 15 sets a current limit value for120 W or 180 W.

FIG. 7 is a flowchart showing an example of an operation procedure ofthe NVDC electric power supply system 1 of this embodiment.

The embedded controller 15 determines the connected AC adaptor 11 (stepC1). When the AC adaptor 11 is the main body side AC adaptor 11A (YES instep C2), the embedded controller 15 sets the current limit value forthe main body side AC adaptor 11A to the charger IC 132 (step C3). Whenthe AC adaptor 11 is the Dock side AC adaptor 11B, the embeddedcontroller 15 sets the current limit value for the Dock side AC adaptor11B to the charger IC 132 (step C4).

It should be noted that, here, although an example in which one of thetwo current limit values is selected is shown, the embedded controller15 can determine three or more types of AC adaptors 11 based on avoltage value of power from the AC adaptor 11 digitized by the ACadaptor A/D converting unit 151, and hence one of three or more currentlimit values may also be selected.

As described above, the NVDC electric power supply system 1 of thisembodiment realizes the safe and efficient use of power from the ACadaptor and power from the battery.

Fourth Embodiment

Next, a fourth embodiment will be described below.

FIG. 8 is a view showing a configuration example of each of thesystem-power supply control unit 131 and charger IC 132 provided in theNVDC electric power supply system 1 of this embodiment.

In FIG. 8, (A) indicates an example of the configuration of the powercircuit 13, and (B) indicates an example of the configuration of thesystem-power supply control unit 131 in the power circuit 13.

As shown in (A) of FIG. 8, in the NVDC electric power supply system 1 ofthis embodiment, the charger IC 132 in the power circuit 13 furtherincludes a mode setting unit 1324. Further, as shown in (B) of FIG. 8,in the system-power supply control unit 131, a step-up/step-down DDconverter is constituted of four FETs (Q1, Q2, Q3, and Q4) to be turnedon/off by the charger IC 132. It should be noted that in also thesystem-power supply control unit 131 in the NVDC electric power supplysystem 1 of each of the first to third embodiments, a step-up/step-downDD converter identical to that described above is constituted.

As described in the first embodiment, the system-power supply controlunit 131 of the power circuit 13 uses the power from the AC adaptor 11and power from the battery pack 12 to create and output the system powerunder the control of the charger IC 132. Further, when the AC adaptor 11is connected, and the battery pack 12 is attached, the voltage value ofthe system power is set to the full-charge voltage value of the batterypack 12.

For example, when the voltage value of power from the AC adaptor 11 isgreater than the full-charge voltage value of the battery pack 12, andthe voltage value of the system power is set to the full-charge voltagevalue of the battery pack 12, it is assumed that the charger IC 132,more specifically, the power control unit 1323 operates thestep-up/step-down DD converter of the system-power supply control unit131 in the step-up/down mode in which the four FETs operate at all timeswhile repeating an on/off action. In the step-up/down mode, the powersupply efficiency is lowered by the power consumption of thestep-up/step-down DD converter, more specifically, the four FETs.

Thus, in the NVDC electric power supply system 1 of this embodiment,paying attention to the fact that when the battery pack 12 is notattached, the voltage value of the system power may not be set to thefull-charge voltage value of the battery pack 12, the charger IC 132switches, under the control of the embedded controller 15, the operationof the step-up/step-down DD converter of the system-power supply controlunit 131 to the step-down mode in which operations of two FETs among thefour FETs are stopped, e.g., the FET Q3 is fixed to the off-state, andFET Q4 is fixed to the on-state. It is assumed that, for example, whenthe voltage value of the system voltage is set to a value less than thefull-charge voltage value of the battery pack 12, the charger IC 132operates the step-up/step-down DD converter of the system-power supplycontrol unit 131 in the step-down mode. That is, the embedded controller15 notifies the charger IC 132 of an instruction to switch the voltagevalue of the system power from the full-charge voltage value of thebattery pack 12 to a value less than the full-charge voltage value ofthe battery pack 12, i.e., an instruction to set a value less than thefull-charge voltage value of the battery pack 12, whereby it is possibleto switch the step-up/step-down DD converter of the system-power supplycontrol unit 131 from the step-up/down mode to the step-down mode. Basedon a voltage value of the system voltage notified by the embeddedcontroller 15, the mode setting unit 1324 determines in which of thestep-up/down mode and step-down mode the step-up/step-down DD converterof the system-power supply control unit 131 should be operated. Thepower control unit 1323 operates the step-up/step-down DD converter ofthe system-power supply control unit 131 in the step-up/down mode orstep-down mode determined by the mode setting unit 1324.

As described above, it is dared not to make the voltage value of thesystem voltage coincident with the full-charge voltage value of thebattery pack 12, the voltage value of the system voltage isintentionally shifted from the full-charge voltage value of the batterypack 12 to, for example, a value less than the full-charge voltage valueof the battery pack 12, the mode is switched from the step-up/down modeto the step-down mode, and operations of two FETs among the four FETsare stopped, whereby it is possible to reduce the power consumed by thestep-up/step-down DD converter of the system-power supply control unit131, and raise the power supply efficiency.

FIG. 9 is a view showing an example of setting of a system power voltagevalue for the charger IC 132 which controls the step-up/step-down DDconverter in the system-power supply control unit 131 by the embeddedcontroller 15.

The system power in FIG. 9 indicates the system power to be created andoutput by the power circuit 13.

As shown in FIG. 9, when the battery pack 12 is attached, the embeddedcontroller 15 sets the voltage value of the system power to a batteryspecification value and, more specifically, to a full-charge voltagevalue of the battery pack 12. On the other hand, when the battery pack12 is not attached, the embedded controller 15 intentionally shifts thevoltage value of the system power from the full-charge voltage value ofthe battery pack 12, and sets the voltage value of the system power to avoltage value at which the step-up/step-down DD converter of thesystem-power supply control unit 131 operates in the step-down mode.

FIG. 10 is a view showing the power supply efficiency of a case whereunder the circumstances in which the battery pack 12 is not attached,the voltage value of the system power is set to the batteryspecification value, i.e., to a value at which the step-up/step-down DDconverter of the system-power supply control unit 131 operates in thestep-up/down mode, and power supply efficiency of a case where thevoltage value of the system power is set to a value intentionallyshifted from the battery specification value, i.e., to a value at whichthe step-up/step-down DD converter of the system-power supply controlunit 131 operates in the step-down mode.

As shown in FIG. 10, the power supply efficiency becomes higher in thecase where the voltage value of the system power is set to a voltagevalue within the range of the step-down mode as compared with the casewhere the voltage value of the system power is set to the full-chargevoltage value of the battery pack 12 irrespective of the powerconsumption of the load.

FIG. 11 is a flowchart showing an example of an operation procedure ofthe NVDC electric power supply system 1 of this embodiment. Thisflowchart shows the operation procedures of the embedded controller 15and BIOS 16 in the case where a change in the connection (attachment)state of the AC adaptor 11 or the battery pack 12 or a change in thecapacity of the battery pack 12 has occurred.

In FIG. 11, steps B1 through B7 are identical to the second embodiment,and hence their descriptions are omitted (see FIG. 5). In the NVDCelectric power supply system 1 of this embodiment, when the AC adaptor11 is connected (YES in step B1), and the battery pack 12 is notattached (NO in step B2), the embedded controller 15 sets ahigh-efficiency mode to the charger IC 132 (step B8). Setting of thehigh-efficiency mode means setting the voltage value of the system powerto the voltage value at which the step-up/step-down DD converter of thesystem-power supply control unit 131 operates in the step-down modedescribed above. By this setting, the charger IC 132 operates thestep-up/step-down DD converter of the system-power supply control unit131 in the step-down mode in which operations of two FETs among fourFETs are stopped.

As described above, the NVDC electric power supply system 1 of thisembodiment realizes the safe and efficient use of power from the ACadaptor and power from the battery.

Fifth Embodiment

Next, a fifth embodiment will be described below.

In the fourth embodiment, when the battery pack 12 is removed, it isdared not to make the voltage value of the system voltage coincidentwith the battery specification value, i.e., the full-charge voltagevalue of the battery pack 12, and the voltage value of the system poweris intentionally shifted to the voltage value at which thestep-up/step-down DD converter of the system-power supply control unit131 operates in the step-down mode in which operations of two FETs amongfour FETs are stopped, whereby the power supply efficiency is raised.

When the battery pack 12 which has been separate from the NVDC electricpower supply system 1 is attached thereto again, the voltage value ofthe system voltage is set to the battery specification value, i.e., tothe full-charge voltage value of the battery pack 12 again. For example,when switching of enhancing the voltage value from a voltage valuewithin the range of the step-down mode to the full-charge voltage valueof the battery pack 12 is performed, a rush current flows, and there isa possibility of the load side being damaged by the overcurrent.

Thus, in the NVDC electric power supply system 1 of this embodiment,when the battery pack 12 is attached on the assumption that the voltagevalue of the system voltage is lowered at the time of removal of thebattery pack 12, the rush current is prevented from flowing. It shouldbe noted that it is assumed that the configurations of the system-powersupply control unit 131 and charger IC 132 provided in the power circuit13 of the NVDC electric power supply system 1 of this embodiment areidentical to the fourth embodiment (see FIG. 8).

As described in the first embodiment, the embedded controller 15 candetect removal or attachment of the battery pack 12 by use of thebattery pack detecting unit 152. Upon detection of attachment of thebattery pack 12, the embedded controller 15 performs setting to thecharger IC 132 to restore the voltage value of the system voltage setfor operating the step-up/step-down DD converter of the system-powersupply control unit 131 in the step-up mode to the specification valueof the battery pack 12, i.e., the full-charge voltage value of thebattery pack 12. At this time, the embedded controller 15 does notabruptly change the system voltage value, and changes the system voltagevalue in, for example, a stepwise manner. For example, the embeddedcontroller 15 controls the charger IC 132 in such a manner that thesystem voltage value is gradually raised in a stepwise manner by anamount of a voltage value (V0−V1 (V)) corresponding to a differencebetween a predetermined voltage value (V1 (V) for convenience' sake) ofthe system set at the time of removal of the battery pack 12 and avoltage value (V0 (V) for convenience' sake) which is the specificationvalue of the battery pack 12 by incrementing the system voltage valueseveral times at certain periodic intervals by an amount for each timeobtained by dividing the above voltage value corresponding to thedifference into several fixed voltage values.

FIG. 12 is a view showing transition of the current value of the systempower of a case where the voltage value of the system power is restoredto the specification value of the battery pack 12 concomitantly withattachment of the battery pack 12.

In FIG. 12, (A) indicates transition of the current value (d1) of thesystem power of a case where the voltage value of the system power isinstantly restored to the specification value of the battery pack 12,and (B) indicates transition of the current value (d2) of the systempower of a case where the voltage value of the system power is restoredto the specification value of the battery pack 12 in, for example, astepwise manner.

As shown in (A) of FIG. 12, when the voltage value of the system poweris instantly restored to the specification value of the battery pack 12,there is a possibility of a rush current flowing. Conversely, as shownin (B) of FIG. 12, when the voltage value of the system power isrestored to the specification value of the battery pack 12 in a stepwisemanner, the rush current can be prevented from flowing.

Further, regarding the restoration of the voltage value of the systempower to the voltage V0 in a predetermined period of time (T1) afterattachment of the battery pack 12, the restoration may be stepwise asdescribed previously or the voltage value may be linearly raised.

FIG. 13 is a flowchart showing an example of an operation procedure ofthe NVDC electric power supply system 1 of this embodiment. Thisflowchart shows the operation procedure of the embedded controller 15 inthe case where the battery pack 12 is attached.

First, the embedded controller initializes the counter value to 0 (stepD1). After initializing the counter value to 0, the embedded controller15 sets a voltage value obtained by incrementing the voltage value ofthe power circuit 13 at that point in time by an amount corresponding toone step value to the charger IC 131 of the power circuit 13 as thevoltage value of the system power (step D2). After performing thissetting, the embedded controller 15 increments the counter value by 1(step D3).

The embedded controller 15 determines whether or not the counter valueafter being incremented by 1 has reached a predetermined value (step D4)and, when the value has not reached the predetermined value (NO in stepD4), the embedded controller 15 sets a timer for securing a timeinterval (step D5). When the timer generates a timeout (YES in step D6),the embedded controller 15 returns to step D2 and increments the voltagevalue of the system power by an amount corresponding to one step value.When the counter value has reached the predetermined value (YES in stepD4), the embedded controller 15 terminates the restoration processing ofthe voltage value of the system power concomitant with the attachment ofthe battery pack 12.

As described above, the NVDC electric power supply system 1 of thisembodiment realizes the safe and efficient use of power from the ACadaptor and power from the battery.

Sixth Embodiment

Next, a sixth embodiment will be described below.

In the NVDC electric power supply system 1 of this embodiment, the modesetting unit 1324 of the aforementioned fourth embodiment further adds afixed mode in which switching is not performed to the DD converter ofthe system-power supply control unit 131, the DD converter beingperformed step-up/step-down switching in the normal mode. For example,when the battery pack 12 is not attached, the FETs Q1 and Q4 are fixedlykept in the on-state at all times at all times, and the FETs Q2 and Q3are fixedly kept in the off-state, whereby the embedded controller 15performs control in such a manner that switching is not performed. Asdescribed above, in the sixth embodiment, a mode setting unit 1325 whichenables switching (load switch mode) to the fixed mode is incorporatedin the charger IC 132.

Switching of the DD converter of the system-power supply control unit131 to the fixed mode is performed by the embedded controller 15 throughthe power control unit 1323 in the charger IC 132. At this time, theembedded controller 15 can perform switching control for the charger IC132 by using the mode pin for switching or wireless communication.

As described above, in the state where the battery pack 12 is notattached, the step-up/step-down DD converter of the system-power supplycontrol unit 131 is shifted to the load switch mode, and thestep-up/step-down operation of the step-up/step-down DD converter is notperformed, whereby it is possible to eliminate the switching loss, andfurther improve the power supply efficiency as compared with the fourthembodiment.

FIG. 14 is a view showing an example of setting of the system powervoltage value by the embedded controller 15 to the charger IC 132 whichcontrols the step-up/step-down DD converter in the system-power supplycontrol unit 131. It should be noted that as in the case of the fourthembodiment, the system power in FIG. 14 indicates the voltage value ofthe system power to be created and output by the power circuit 13.

As shown in FIG. 14, when the battery pack 12 is attached, the embeddedcontroller 15 sets the voltage value of the system power to the batteryspecification value, more specifically, to the full-charge voltage valueof the battery pack 12. On the other hand, when the battery pack 12 isnot attached, the embedded controller 15 shifts the step-up/step-down DDconverter of the system-power supply control unit 131 to the load switchmode, whereby the embedded controller 15 sets the voltage value of thesystem power to the adaptor specification value, more specifically, tothe voltage value of the power from the AC adaptor 11.

FIG. 15 is a flowchart showing an example of an operation procedure ofthe NVDC electric power supply system 1 of this embodiment. Thisflowchart shows the operation procedures of the embedded controller 15and BIOS 16 in the case where a change in the connection (attachment)state of the AC adaptor 11 or the battery pack 12 or a change in thecapacity of the battery pack 12 has occurred.

In FIG. 15, steps B1 through B7 are identical to the second embodiment,and hence their descriptions are omitted (see FIG. 5). In the NVDCelectric power supply system 1 of this embodiment, when the AC adaptor11 is connected (YES in step B1), and the battery pack 12 is notattached (NO in step B2), the embedded controller 15 performs setting ofthe load switch mode to the charger IC 132 (step B9) in place of thehigh-efficiency mode (step B8 of FIG. 11) of the fourth embodiment. Bythis setting, the charger IC 132 shifts the step-up/step-down DDconverter of the system-power supply control unit 131 to the load switchmode in which operations of all the four FETs are stopped.

As described above, the NVDC electric power supply system 1 of thisembodiment realizes the safe and efficient use of power from the ACadaptor and power from the battery.

Seventh Embodiment

Next, a seventh embodiment will be described below.

FIG. 16 is a view showing an example of a configuration of the NVDCelectric power supply system 1 of this embodiment.

As described in the first embodiment, a case where this NVDC electricpower supply system 1 is applied to a notebook PC to/from which anextension unit incorporating therein an ODD can freely beattached/detached is assumed.

As shown in FIG. 16, in the NVDC electric power supply system 1 of thisembodiment, the power circuit 13 further includes a power supply-linebifurcating unit 133, and switch 134 for switching one of power supplylines bifurcated by the power supply-line bifurcating unit 133 betweenthe on-state and off-state.

When the extension unit is attached to the notebook PC, power is inputfrom the Dock side AC adaptor 11B. Further, as described in the firstembodiment, the rating of the Dock side AC adaptor 11B regarding whichit is conceivable that the power can be consumed by the ODD and the likeis set larger than the rating of the main body side adaptor 11A. Whenthe power from the AC adaptors 11 including the Dock side AC adaptor 11Bis supplied to the extension unit which is part of the load through thesystem-power supply control unit 131, an increase in the size of the FETis caused by the high-current countermeasures taken in the system-powersupply control unit 131, and lowering of the power supply efficiency iscaused by the switching loss.

Thus, in the NVDC electric power supply system 1 of this embodiment,only when power is input from the Dock side AC adaptor 11B, one of thepower supply lines bifurcated by the power supply-line bifurcating unit133 is led to the extension unit side without being passed through thesystem-power supply control unit 131. The other of the power supplylines bifurcated by the power supply-line bifurcating unit 133 is led tothe system-power supply control unit 131 as before, and the system powercreated and output by the system-power supply control unit 131 issupplied to the load on the main body side.

One of the power supply lines bifurcated by the power supply-linebifurcating unit 133 is switched between the on-state (conduction) andoff-state (shutdown) by the switch 134 under the control of the embeddedcontroller 15. One of the power supply lines bifurcated by the powersupply-line bifurcating unit 133 and the power supply line configured tosupply the system power created and output by the system-power supplycontrol unit 131 to the load are connected in parallel with each otherwith a thyristor interposed between them, and the power of one of thetwo lines is supplied to the load on the extension unit side.

When the power is input from the Dock side AC adaptor 11B, the embeddedcontroller 15 which can determine the type of the AC adaptor 11 by useof the AC adaptor A/D converting unit 151 turns the switch 134 on.Thereby, part of the power from the Dock side AC adaptor 11B isbifurcated by the power supply-line bifurcating unit 133 and isthereafter supplied to the load on the extension unit side without beingpassed through the system-power supply control unit 131. On the otherhand, when the power is input from the main body side AC adaptor 11A,the embedded controller 15 turns the switch 134 off. Thereby, thebifurcation formed by the power supply-line bifurcating unit 133 issubstantially nullified, and the power created and output by thesystem-power supply control unit 131 is supplied to the load on theextension unit side together with the load on the main body side.

As described above, by virtue of the configuration in which only thepower from the Dock side AC adaptor 11B is bifurcated by the powersupply-line bifurcating unit 133, and control of the embedded controller15, it is possible to prevent the size of the FET from being increasedby the high-current countermeasures taken in the system-power supplycontrol unit 131, and prevent the power supply efficiency from beinglowered by the switching loss.

FIG. 17 is a flowchart showing an example of an operation procedure ofthe NVDC electric power supply system 1 of this embodiment.

First, the embedded controller determines presence/absence of connectionof the AC adaptor 11 (step E1). When the AC adaptor 11 is connected (YESin step E1), the embedded controller 15 determines the type of theconnected AC adaptor (step E2). When the connected AC adaptor is themain body side AC adaptor 11A (YES in step E3), the embedded controller15 turns the switch 134 of the power circuit 13 off (step E4). Also whenthe AC adaptor 11 is not connected (NO in step E1), the embeddedcontroller 15 turns the switch 134 of the power circuit 13 off (stepE4). On the other hand, when the connected AC adaptor is the Dock sideAC adaptor 11B (NO in step E3), the embedded controller 15 turns theswitch 134 of the power circuit 13 on (step E5).

As described above, the NVDC electric power supply system 1 of thisembodiment realizes the safe and efficient use of power from the ACadaptor and power from the battery.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions.

What is claimed is:
 1. An electric power supply system comprising: apower circuit that comprises a step-up/step down DD converter, creates athird power to output to a load using a first power from an adaptor anda second power from a battery, and outputs the third power to the load;and an embedded controller that detects a presence or an absence of thebattery, wherein the embedded controller switches the step-up/step-downDD converter of the power circuit from a step-up/down mode to astep-down mode when the embedded controller detects removal of thebattery, the step-up/down mode performs switching operations of allswitching elements of the step-up/step-down DD converter continuously,and the step-down mode stops switching operations of at least one of theswitching elements of the step-up/step-down DD converter, the powercircuit determines an operating mode of the step-up/step-down DDconverter according to a voltage set value indicative of a first voltagevalue of the third power to be created, and the embedded controller setsa full-charge voltage value of the battery as the voltage set value whenthe battery is attached, and sets a second voltage value as the voltageset value when the battery is removed, the full-charge voltage value ofthe battery being a value at which the step-up/step-down DD converteroperates in the step-up/down mode, the second voltage value being avalue different from the full-charge voltage value of the battery and atwhich the step-up/step-down DD converter operates in the step-down mode.2. The electric power supply system of claim 1, wherein the embeddedcontroller updates the voltage set value in a stepwise manner from thesecond voltage value set at a time of the detection of the removal ofthe battery to the full-charge voltage value of the battery when theembedded controller detects attachment of the battery.
 3. An electricpower supply system comprising: a power circuit that comprises astep-up/step-down DD converter, the power circuit creates a third powerto output to a load using a first power from an adaptor and a secondpower from a battery, and outputs the third power to the load; and anembedded controller that detects a presence an absence of the battery,wherein: the embedded controller switches the step-up/step-down DDconverter of the power circuit from a step-up/down mode to a load switchmode when the embedded controller detects removal of the battery, thestep-up/down mode performs switching operations of all of switchingelements of the step-up/step-down DD converter continuously, the loadswitch mode stops switching operations of all of the switching elementsof the step-up/step-down DD converter, the power circuit determines anoperating mode of the step-up/step-down DD converter according to avoltage set value indicative of a first voltage value of the third powerto be created, and the embedded controller sets a full-charge voltagevalue of the battery as the voltage set value when the battery isattached, and sets a second voltage value as the voltage set value whenthe battery is removed, the full-charge voltage value of the batterybeing a value at which the step-up/step-down DD converter operates inthe step-up/down mode, the second voltage value being a value differentfrom the full-charge voltage value of the battery and at which thestep-up/step-down DD converter operates in the load switch mode.
 4. Anelectric power supply system comprising: a power circuit that comprisesa step-up/step-down DD converter, the power circuit creates a thirdpower to output to a first load using a first power from an adaptor anda second power from a battery, and outputs the third power to the firstload; and an embedded controller that determines a type of the adaptorbased on a voltage value of the first power, wherein: the power circuitcomprises a bifurcation circuit that intervenes between the adaptor andthe step-up/step-down DD converter, and bifurcates the first power tosupply a portion of the first power to a second load without passing theportion of the first power through the step-up/step-down DD converter,the power circuit comprises a switch that selects one of a first pathwayor a second pathway, the first pathway being a pathway through which theportion of the first power bifurcated by the bifurcation circuit issupplied to the second load without being passed through thestep-up/step-down DD converter, the second pathway being a pathwaythrough which a second portion of the first power bifurcated by thebifurcation circuit is supplied to the second load together with thesecond power from the battery through the step-up/step-down DD converteras the third power, and the embedded controller controls the switchaccording to the type of the adaptor.